The present invention relates to the general field of turbomachines in which the shaft of the low-pressure spool comprises a turbine shaft assembled to a stub axle of a compressor shaft. The invention relates more precisely to an assembly of this type that is radially compact.
In a turbomachine, the gas coming from combustion of an air/fuel mixture drives the low-pressure turbine in rotation. This turbine has a low-pressure turbine shaft that is coupled to a low-pressure compressor shaft in order to rotate the low-pressure compressor of the turbomachine. For this purpose, the high-pressure turbine shaft is housed inside a stub axle of the low-pressure compressor shaft which is coupled thereto by fluting. A nut is tightened onto the downstream end of the low-pressure turbine shaft and serves to hold this coupling together, axially. More precisely, the stub axle of the low-pressure compressor shaft presents an internal annular collar that comes into abutment radially against the high-pressure turbine shaft and into abutment axially against the clamping nut.
That type of assembly presents the drawback of possessing a radial size that is relatively large. This size comes both from the thickness needed for tightening the nut on the low-pressure turbine shaft and the thickness needed for obtaining a bearing surface of sufficient size between the low-pressure turbine shaft and the stub axle of the low-pressure compressor shaft. Such radial size is particularly harmful when dimensioning low-pressure turbine shafts for a contra-fan type turbomachine (i.e. when there are two contrarotating fans mounted at the front).